Complementarity and correlations

TL;DR

This paper interprets entanglement through classical correlations of complementary properties, showing that entangled states exhibit stronger correlations than certain classical states, with implications for understanding quantum correlations.

Contribution

It introduces a correlation-based interpretation of entanglement and reveals that all separable nonclassical states have weaker correlations than some classical states.

Findings

Entangled states have correlations beyond a threshold, indicating entanglement.

Separable nonclassical states exhibit smaller correlations than some classical states.

The results are based on mutual information, with conjectures about other measures.

Abstract

We provide an interpretation of entanglement based on classical correlations between measurement outcomes of complementary properties: states that have correlations beyond a certain threshold are entangled. The reverse is not true, however. We also show that, surprisingly, all separable nonclassical states exhibit smaller correlations for complementary observables than some strictly classical states. We use mutual information as a measure of classical correlations, but we conjecture that the first result holds also for other measures (e.g. the Pearson correlation coefficient or the sum of conditional probabilities).